<template>
  <el-color-picker
    v-model="theme"
    :predefine="[
      '#409EFF',
      '#1890ff',
      '#304156',
      '#212121',
      '#11a983',
      '#13c2c2',
      '#6959CD',
      '#f5222d',
    ]"
  />
</template>

<script>
const version = require("element-ui/package.json").version;
const ORIGINAL_THEME = "#409EFF"; // 这是默认的颜色
export default {
  data() {
    return {
      chalk: "",
      theme: localStorage.getItem("ORIGINAL_THEME") || ORIGINAL_THEME,
    };
  },
  watch: {
    theme: {
      immediate: true,
      async handler(val, oldValue) {
        localStorage.setItem("ORIGINAL_THEME", val);
        const oldVal = this.theme;
        console.log(val);
        if (typeof val !== "string") return;
        const themeCluster = this.getThemeCluster(val.replace("#", ""));
        const originalCluster = this.getThemeCluster(oldVal.replace("#", ""));
        const $message = this.$message({
          message: "  Compiling the theme",
          customClass: "theme-message",
          type: "success",
          duration: 0,
          iconClass: "el-icon-loading",
        });

        const getHandler = (variable, id) => {
          const originalCluster = this.getThemeCluster(
            ORIGINAL_THEME.replace("#", "")
          );
          const newStyle = this.updateStyle(
            this[variable],
            originalCluster,
            themeCluster
          );
          let styleTag = document.getElementById(id);
          // console.log(variable);
          // console.log(newStyle);
          if (!styleTag) {
            styleTag = document.createElement("style");
            styleTag.setAttribute("id", id);
            document.head.appendChild(styleTag);
          }
          styleTag.innerText = newStyle;
        };

        // 有些版本请求有问题，测试请求 2.15.6
        const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`;
        await this.getCSSString(url, "chalk");

        getHandler("chalk", "chalk-style");

        const styles = [...document.querySelectorAll("style")].filter(
          (style) => {
            const text = style.innerText;
            return /oldVal/i.test(text) && !/Chalk Variables/.test(text);
          }
        );
        styles.forEach((style) => {
          const { innerText } = style;
          if (typeof innerText !== "string") return;
          style.innerText = this.updateStyle(
            innerText,
            originalCluster,
            themeCluster
          );
        });

        $message.close();
      },
    },
  },
  methods: {
    updateStyle(style, oldCluster, newCluster) {
      let newStyle = style;
      oldCluster.forEach((color, index) => {
        newStyle = newStyle.replace(new RegExp(color, "ig"), newCluster[index]);
      });
      return newStyle;
    },

    getCSSString(url, variable) {
      return new Promise((resolve) => {
        const xhr = new XMLHttpRequest();
        xhr.onreadystatechange = () => {
          if (xhr.readyState === 4 && xhr.status === 200) {
            this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, "");
            resolve();
          }
        };
        xhr.open("GET", url);
        xhr.send();
      });
    },

    getThemeCluster(theme) {
      const tintColor = (color, tint) => {
        let red = parseInt(color.slice(0, 2), 16);
        let green = parseInt(color.slice(2, 4), 16);
        let blue = parseInt(color.slice(4, 6), 16);

        if (tint === 0) {
          // when primary color is in its rgb space
          return [red, green, blue].join(",");
        } else {
          red += Math.round(tint * (255 - red));
          green += Math.round(tint * (255 - green));
          blue += Math.round(tint * (255 - blue));

          red = red.toString(16);
          green = green.toString(16);
          blue = blue.toString(16);

          return `#${red}${green}${blue}`;
        }
      };

      const shadeColor = (color, shade) => {
        let red = parseInt(color.slice(0, 2), 16);
        let green = parseInt(color.slice(2, 4), 16);
        let blue = parseInt(color.slice(4, 6), 16);

        red = Math.round((1 - shade) * red);
        green = Math.round((1 - shade) * green);
        blue = Math.round((1 - shade) * blue);

        red = red.toString(16);
        green = green.toString(16);
        blue = blue.toString(16);

        return `#${red}${green}${blue}`;
      };

      const clusters = [theme];
      for (let i = 0; i <= 9; i++) {
        clusters.push(tintColor(theme, Number((i / 10).toFixed(2))));
      }
      clusters.push(shadeColor(theme, 0.1));
      return clusters;
    },
  },
};
</script>

<style></style>
